In an LED lighting device used for a lighting equipment, a plurality of light emitting diodes (LEDs) are used to obtain a required amount of light output. Here, if the light emitting diodes are series-connected, direct voltage supplied to the LEDs becomes high. If the LEDs are connected in parallel, current supplied to the diodes becomes large. Therefore, a plurality of light emitting diodes are connected in an appropriate series-parallel circuit in an LED lighting device.
If the light emitting diodes are connected in series-parallel, current flown to each of the LED load circuits connected in series-parallel must be balanced to uniformize light output from the plurality of light emitting diodes. For example, as shown in Japanese Laid-Open Patent Publication No. 2008-130295, an LED lighting circuit for collectively constant current controlling the current flowing in each of LED modulized the LED load circuits has been proposed. In the LED lighting circuit of this conventional art, control elements (transistors) configuring a current mirror circuit are provided in series to each of the LED load circuits, a control micro computer judges a circuit with the highest sum of on-voltage of the light emitting diodes, and on the basis thereof interlocks the energization current value of remaining circuits to balance between each of the LED load circuits.
In the LED lighting circuit described in the above-mentioned Japanese Laid-Open Patent Publication No. 2008-130295, control elements of a current mirror circuit are connected in series to an LED load circuit and therefore when current flows through the LED load circuit, power consumption is generated by multiplication of voltage between both edges of the control element and the current which flows through the LED load circuit. As a result thereof, there is a disadvantage that the power consumption becomes a loss and power efficiency of the LED lighting device is decreased.
The present invention aims to provide an LED lighting device by which power loss in a current control circuit for limiting current which flows into light emitting diodes is not easily generated and current flowing to the light emitting diodes can be controlled and a lighting equipment including the LED lighting device.